Traditional methods of supplying electric power have drawbacks. First, environmental costs associated with fossil-fuel based electric power sources, such as coal, are drawing increasing concern. It is expensive to mitigate the environmental effects of these sources. Second, because fossil-fuel based sources are nonrenewable, scarcity will eventually result in higher costs for these sources unless aggregate demand for them is reduced.
Transmission of the electricity from the power generation source through the power grid to the point of end use is also a challenge. Transmission lines involve many costs, include fabricating the transmission equipment, installing the transmission lines on property above or below ground, and complying with myriad regulatory requirements. In addition, the time required to install transmission lines may reduce or eliminate the ability of the energy installation, such as a wind farm, to begin producing revenue.
In addition, the installation of a single transmission line often requires the coordination of multiple private entities and state and local governments. In addition, power loss associated with supplying electricity through the transmission line adds to the total cost. These factors constrain the location of power generation sources in relation to the points of end use.
Yet another challenge of traditional electric power supply lies in the variability of demand. Power systems must be built to handle large variability of demand, and to adequately supply power during periods of peak demand. For example, a warm summer afternoon on a weekday results in high demand for electricity, as residential, industrial, and commercial users of electricity all require relatively larger amounts of power at the same time. Traditional power grids lack energy storage capacity to store electricity to deal with variability of demand. Consequently, additional costs must be incurred to build extra power generating capacity than is needed on average, in order to ensure that capacity exists to meet demand at peak times.
Certain fossil fuel based power generation plants, such as coal-fired plants, often require a lead-time before fully coming online to deliver power to a power grid. This may be due to the need to prepare the power plant to deliver power. Therefore, in order to deliver power more quickly to a power grid when needed on short notice, a fossil-fuel power plant may burn fuel to remain in standby in order to quickly respond to changes in power demand. This adds to the total power generation cost and increases emissions.
Renewable electricity generation technologies are rapidly being developed to mitigate some of the above concerns. However, many renewable sources of energy (e.g., wind, tidal, and/or solar energy) are inherently intermittent. Thus, while renewable energy technologies address some of the problems of electric power generation, they also create additional problems. The variability in renewable power supply can lead to greater need to keep fossil-fuel based sources ready to provide incremental demand, which, as noted above, has both monetary and environmental costs.
Variability of supply, coupled with the costs and difficulty associated with building transmission lines, poses a particular challenge for wind energy. The best locations to site a wind turbine, containing the highest amount of consistent wind, are sometimes located far from the locations where the energy is to be used. The optimal generating sites may also be remote to existing transmission lines, necessitating the construction of additional new transmission infrastructure. Because there is a loss of electrical energy associated with transmission lines that may be proportional to the distance of the transmission line, the availability of new or existing transmission line capacity may compel the wind farm to be sited at a suboptimal location, where the variability of wind is a large economic concern. In addition, the timing of the availability of wind may not correlate to the time periods of peak demand for power use.
Methods and systems are being developed to address the dual variability in supply and demand for electricity from renewable sources. For example, there are various efforts aimed at storing solar or wind-generated electricity in energy storage devices, such as in underground compressed air tanks or in spinning flywheels. While these systems allow energy to be used at times of more optimal demand than at the time of power generation, these methods still require a full transmission line infrastructure in place to transport the energy to the power grid and ultimately to end users.
The present disclosure is directed to overcoming or mitigating one or more of the problems set forth above.